The present invention relates to an apparatus comprising an eductor for dissolving a gas in a liquid. More specifically, the present invention relates to an efficient apparatus comprising an eductor in combination with an upstream flat plate orifice in-line mixing device to produce an extremely synergistic increase in the amount of a gas dissolved in a liquid.
Heretofore, numerous different types of mixing devices have been utilized to aerate a liquid or increase the amount of a gas dissolved in the liquid. Such devices have been used in several fields including the waste treatment field wherein air or oxygen is usually added to waste water in aerobic processes to lagoons, equalization basins, dechlorinated effluent, holding tanks, and the like. Generally, the efficiency of the prior art devices is extremely low usually ranging from 3 percent to only about 7 or 8 percent. However, according to the present invention, an aeration efficiency of the amount of gas dissolved compared to the amount of gas added to a liquid is at least 20 or 30 percent and can range up to 90 percent and even 100 percent.
An example of a particular prior art air diffuser unit for aerating sewage is set forth in U.S. Pat. No. 3,441,216 granted Apr. 29, 1969 to R. J. Good. In this patent, a cage having a head is completely immersed in sewage. The head has a hole for the flow of air therethrough to an annular array of rods having their ends secured to the head. A fabric sock extends over the rods and serves as a diffuser for injecting air into the sewage effluent. This patent is not pertinent in that it relates to a totally different structure as well as concept.
Another patent of interest in U.S. Pat. No. 3,865,721, granted Feb. 11, 1975 to Joseph R. Kaelin. This patent relates to a method of introducing circulating oxygen or air in the liquid present in an activated sludge tank of a waste treatment plant to prevent sludge settlement. Basically, this device relates to an annular cylindrical part located in the basin. A shaft, which is connected to a motor, has an end extending into the annular cylinder with blades located on this end. A feed pipe extends upwardly into the lower end of the cylinder and generally carries activated sludge therein. Additionally, feed pipes of oxygen or air are introduced either into the feed pipe or the bottom of the annular cylinder. Thus, upon activation of the motor, the blades or propellers tend to aerate the liquid. This patent is not pertinent in that it does not contain applicant's specific structure for an eductor and furthermore lacks any suggestion of combination with an in-line mixing device such as a flat plate orifice.